Leaking gear oil from top of speedo cable

So don't know if this is a common fault or am just missing something simple here -

My gear oil has started leaking from my 1983 MK1 GTI gearbox from where the speedo cable enters the box - I replaced the seal between the cable and the box but it still seems to leak and the oil is sitting on top of the bracket and leaking down?

Also it only leaks when the car has warmed up?

I have read it may be overfilled in the past so drained out any excess oil from the fill point on the side of the box while flat on the floor yet it still leaks?

What else am I missing or do I need to replace the whole cable now as there is an internal seal maybe?

Thank you for any help in advanced

MIT 

I had this trouble, from memory I replaced an 'O' ring with one from an old Lister diesel engine spares pack and it fixed it, yours probably only leaks when warm because the oil is being thrown around inside.
Have you got the right screw holding it, it's an unusual size and hard to find.

Thanks for the reply - I have ordered a new O ring and replacement outer seal again from Heritage so hopefully this should solve it then - When you say the right screw do you mean the bolt holding it in as thats the same bolt that has always been there and I have had the car for over 18 years now without this issue before.

Will update this post soon as the bits come to see if it does resolve my issue - thanks for your help - hopefully the O-ring with a new outer seal works lol  

Your new seals will fix it.
The screw is an unusual thread, I can't remember the exact size, it could have been 7mm x 1mm pitch, the screws holding the small cover at the bottom of the bell housing are the same, I had a 6mm in mine and it could well have been me who put it there.

It worked! For anyone that replaces the seal on the speedo -

The drive gear should pull off as there's a small spring loaded clip that holds it in place inside the gear cog - once off push up the seal and refit the drive gear onto the cable - you can also try spin the gear and have a helper check the clocks to see if the needle jumps to ensure it's located correctly - 

All sorted now😎

Thanks everyone for your help  

Great news  

Take care removing the Cable I have never had the bad experience, but it has been reported that when some Dubbers removed theirs, they had to tug on the cable as it was stuck, and the clip fell off and they ended up with the gear still in the transmission.  If you have that issue Jack one wheel place the Tranny in gear and rotate a wheel a bit one way, throw it in reverse, then back in 1st and rotate it and back a bit..Tends to take the tension off the Cable…

My experience is that any time I would slightly move the cable or look at it, the blasted thing would "POP" off the back of the speedo.

Good work and telling folks how you did it.

I'm just about to refit my cable, does the small  O ring just sit below the collar that holds the circlip? (I've tried to show in show in red on the pic below?)